| --! qt:dataset:src |
| set hive.mapred.mode=nonstrict; |
| set hive.explain.user=false; |
| -- SORT_BEFORE_DIFF |
| -- union case: all subqueries are a map-only jobs, 3 way union, same input for all sub-queries, followed by reducesink |
| |
| explain |
| select count(1) FROM (select s1.key as key, s1.value as value from src s1 UNION ALL |
| select s2.key as key, s2.value as value from src s2 UNION ALL |
| select s3.key as key, s3.value as value from src s3) unionsrc; |
| |
| select count(1) FROM (select s1.key as key, s1.value as value from src s1 UNION ALL |
| select s2.key as key, s2.value as value from src s2 UNION ALL |
| select s3.key as key, s3.value as value from src s3) unionsrc; |